Moviegoers elected Chris Rock's political spoof Head of State the most popular film in the country over the weekend. The comedy, co-starring Bernie Mac, opened at No. 1 with $14 million. Bringing Down the House slipped to second with $12.5 million, followed by new action flick The Core (No. 3 with $12.4 million) and John Travolta's latest career killer Basic (No. 4 with $12.1 million). Oscar winners Chicago and The Pianist, meanwhile, received nice boosts. Chicago (No. 5 with $7.4 million) was up 20 percent from last weekend, and The Pianist (No. 9 with $2.4 million) entered the top 10 for the first time.